It looks like you're doing a lot of implicit type conversions. What type (int, bigint, varchar, ...) is CPON.Inquiries. Hopefully it's some numerical like int or bigint. If so, change it in your temp table (#tempHW) to match. OTOH, if you're wrapping the Inquiry Number with "[" and "]" 'cos it's done like that in CPOA, then do a pre-query to change the field content in every row of the temp table #tempHW - it'll be lots quicker than doing it row by row during the query!

Also, why are you doing this:

CUST.[Customer PO] LIKE #tempHW.[CPO Number] + '%'

I would have thought that wither your customer number should match or not match, and that you were only interested in the ones that matched, so changing that to

CUST.[Customer PO] = #tempHW.[CPO Number]

will speed things up tremendously.

Finally, I'd advice putting an index on your temp table:

create index idx_tempHW on #tempHW([Inquiry Number], [CPO Number])

and then run the query. You should find that you don't need the "(nolock)" hints (which are, really, when you think about it) just a way of saying "get me an answer - I don't care if it's right or not" !)

Ransomware has become a major concern for organizations; its prevalence has grown due to past successes achieved by threat actors. While each ransomware variant is different, we’ve seen some common tactics and trends used among the authors of the malware.

As commented already by other experts, both the joins involve inefficiencies.
We need to work on how to minimize/eliminate those inefficiencies.

CPON.Inquiries = '[' + #tempHW.[Inquiry Number] + ']'
Either add column in dbo.CPOA CPON table, of type number, to hold Inquiry Number without brackets, create index on this column and use it in join.
Alternatively, add a column in temp table tempHW, of type varchar, to hold Inquiry Number bracketed by square brackets, create index on this column and use it in join. This, I think is more acceptable solution as it it does not modify the structure of any permanent tables for de-normalization for performance.

CUST.[Customer PO] LIKE #tempHW.[CPO Number] + '%'
I think this join may not be as costly as the first one. If query continues to be slow after implementing the change suggested above, then
Add column in CUST table to hold first part of PO Number separately, create index on this column and use in join.
Sadly, I can not think of solution where you can make some change in temp table structure instead of main CUST table.

Do you experience same slowness for select query with same joins?
If not, then I guess issue is somewhere else.
If yes, then use select query to do the experimentation suggested above.

Store the [Inquiry Number] in #tempHW during initial load in the same format as it will be joined in. In fact, all other functions -- such as RTRIM, LTRIM, etc. -- should also be done once during the initial load, not in every join afterward.

Also, use a clustered index on the temp table, not a nonclustered.

But, for this time, since the temp table and its index already exists, we have to correct that first before the main query:

Featured Post

See how one of the leading financial services organizations uses Recorded Future as part of a holistic threat intelligence program to promote security awareness and proactively and efficiently identify threats.

Viewers will learn how to use the UPDATE and DELETE statements to change or remove existing data from their tables.
Make a table:
Update a specific column given a specific row using the UPDATE statement:
Remove a set of values using the DELETE s…